Startup Idea : Video game preorders based on Time Discount

I'm thinking of this model of selling video games. Many sellers offer oportunity to buy a game before the release date. But I would like to focus only on those preorders, because I think, that customers, that preordered the product deserve something more. I mean time discount. The price of the video games would increase each day by little amount till the standard/normal price on release day. Logic is very simple: The sooner you buy, the less you pay.